The most common construction of a pressure gauge utilizes a Bourdon tube as the pressure transfer mechanism for a pressure sensor. In measurement of high pressure, that is, in ranges over 1,000 pounds per square inch, the use of Bourdon gauges seems to be the exclusive means of constructing pressure gauges.
A Bourdon gauge has one feature that limits its use for certain applications. It depends upon the pressure media entering the Bourdon tube as a means of generating a deflection to indicate pressure. Some industries require extremely clean pressure instruments and contamination of the pressure media is detrimental to the fluid being measured. In the plastic industry, the hot plastic melt must be prevented from entering a pressure gauge since, upon cooling, the plastic solidifies and in turn renders the gauge useless.